1. Field of the Invention
The present invention relates to a thermostat for use with an oven and more particularly for an electronic thermostat for use with an oven that may include a self-cleaning feature.
2. Background Art
The majority of cooking ovens in the present state of the art utilize electro-mechanical devices as thermostats to sense and subsequently control oven cavity temperature. Most of these units utilize a capillary tube device to sense oven cavity temperature wherein the expanding liquid in the system expands a diaphragm when hot and controls a switch to turn the heating elements on or off. Usually in such an arrangement, temperature swings are not tightly controlled and the control is accurate only at such time as when initially calibrated.
It has been determined by means of field service data, reliability of such mechanical devices is not as good as expected by the stove and oven industry. It has long been felt that by means of electronic circuitry, a substantial improvement can be made in accuracy, control and reliability over mechanical thermostats as described above. A certain amount of electronic controls have been developed in the field of oven temperature regulation. It is noted that many of these utilize keyboards or rotary encoders for input and electronic displays for user feedback. Such techniques utilize calibrated knobs similar to that of the mechanical counterpart. The consumer is unable to determine from the controls as presented that electronic circuitry is utilized in such arrangements.
Other techniques employed in the area of oven thermostats include the use of a bi-metallic sensing element that operates to close or open an electrical contact to control a circuit to an electronic heating oven or in the case of a gas fired unit the bi-metallic element may be employed to control a movable valve member for controlling fuel control to the burner in response to the sensed oven temperature. Yet another technique includes the use of a bi-metallic element heated by an electrical current in response to a thermistor in the oven for sensing oven temperature. The bi-metallic element mechanically operates the fuel gas valve and electrical relay for energizing or deenergizing the appropriate fuel valve.
A background art search directed to the subject matter of this application and conducted in the U.S. Patent and Trademark Office disclosed the following U.S. Pat. Nos.:
4,493,980 PA1 4,524,264 PA1 4,948,950 PA1 4,958,062 PA1 5,040,724 PA1 5,053,605 PA1 5,126,536 PA1 5,256,860
None of the above patents disclosed an oven temperature regulating electronic thermostat which effectively senses the oven cavity temperature including a linear potentiometer set to cook and clean temperatures. In the present arrangement, voltage is generated to control a relay to cycle the heating element to maintain the oven cavity temperature. It is also usable in both gas or electric cooking ovens, even those which may include a self-cleaning feature to control both the cook and clean temperatures.